As a pressure vessel made of a synthetic resin for containing various gases, liquefied gases or the like, various configurations having a liner body and a FRP layer covering the outer surface of the liner body have been suggested.
The pressure vessel is provided with a stock that forms a gas entrance. In many cases, the stock is made of metal.
Patent Document 1 discloses a pressure vessel having a configuration in which a liner body is formed by blow-molding, and a flange section included in the stock overlaps the inner surface of the liner body. FIGS. 10 and 11 are a cross-sectional view and a diagram illustrating a manufacturing process of the pressure vessel of Patent Document 1, respectively.
As in FIG. 10, the pressure vessel 5 disclosed in Patent Document 1 has a vessel main body section constituted of a liner body 1 formed by blow-molding, an FRP layer 2 covering an outer surface of the liner body 1, and a stock 3 provided in the vessel main body section. The stock 3 has a cylindrical section 3b having a gas entrance 3a and a flange section 3c that is formed to spread from a vessel inner end (a lower end in FIG. 10) side of the cylindrical section 3b along an inner surface of the liner body 1. An adhesive resin layer 4 is interposed between the stock 3 and the liner body 1. In addition, Patent Document 1 discloses that the adhesive resin layer 4 is formed of polyethylene-based thermoplastic resin to enhance the adhesive strength between the liner body 1 and the stock 3.
Patent Document 1 discloses the method described below, as a method of manufacturing the pressure vessel 5. First, as illustrated in FIG. 11, the stock 3 is supported by a support rod 6 and disposed between a pair of liner body molding dies 7, and a parison 9 in a cylindrical shape is suspended from the die 8 of a blow-molding machine around an outer circumferential surface of the stock 3. Next, the pair of dies 7 is clamped. The parison 9 in soft state is pressed against the outer surface of the stock 3 by the die clamping. The adhesive resin 4 provided on the outer surface of the stock 3 melts by heat of the parison 9, and the parison 9 and the stock 3 are bonded to each other. By blowing air into the parison 9 to inflate the parison 9 and press it against the inner surface of the dies 7, the liner body 1 is molded. After demolding, the outer surface of the liner body 1 is covered with fiber yarns, bundles or mats, such as carbon fiber yarns or bundles, and glass fiber yarns or bundles in which thermosetting resin such as epoxy resin and unsaturated polyester resin is impregnated, which is cured to form the FRP (CFRP, GFRP or the like) layer 2.
Since the pressure vessel 5 disclosed in Patent Document 1 is easily manufactured by blowing the interior of the parison 9 after disposing the stock 3 between the pair of dies 7 and clamping the dies. In this respect, it is possible to reduce the manufacturing cost, compared to the known synthetic resin pressure vessels manufactured by disposing a stock (or a cap) on the outer surface of the liner body and welding the cap on the liner body by spin-welding.